1. Field of the Invention
The present invention generally relates to positive displacement gear pumps, and more particularly to a magnetically driven gear pump of simplified construction having a magnet and rotor assembly and an offset stationary shaft on which two respective gears rotate.
2. Discussion of the Prior Art
In many pumping applications, it is desirable to avoid potential seal leakage by not using seals in conjunction with rotating parts. Accordingly, it has become more common in the pump arts to employ a magnetic drive system to eliminate the need for seals along rotating surfaces. While such pumps may still employ static seals, because of their lack of dynamic or rotational seals, they have become known as a “sealless” pump. Indeed, magnetic drive structures have been used in the design of positive displacement gear pumps as well.
In some prior art magnetically driven gear pumps, it is common to have a driven shaft on which is mounted at least one of the gears, generally referred to as a rotor. In turn, to support such a rotatable shaft, it is common to use an additional pump housing section or bracket between the magnetic drive components and the portion of the pump housing that contains the gears. Such pumps also tend to have the second or idler gear rotate on a fixed shaft. The fixed shaft may be mounted at one end within the head of the pump housing.
In the prior art pumps, the bracket that is needed to support the rotatable shaft for the rotor, along with the extra length of components including the rotatable shaft, add to the overall length and weight of such pumps. Moreover, the separate rotating rotor shaft and stationary shaft for the idler gear add to the complexity of the structures and tolerances necessary to make a successful, reliable pump. It would be desirable to simplify and reduce the size and weight of such magnetically driven gear pumps.
The present invention addresses shortcomings in prior art gear pumps, while providing the above mentioned desirable features in magnetically driven gear pumps.